PROJECT SUMMARY ?Adaptation and pilot study of yoga to reduce depression in adolescents? Recent reports have shown an alarming increase in prevalence of depression in adolescents, particularly girls, as well as increased numbers of untreated depression in adolescents. This is true despite improved access to health care from 2000 to 2014 across all socioeconomic groups and data supporting more efficacious treatment of depression in adolescents. Thus, testing alternative approaches to treating depression in adolescents, including approaches that do not rely on the limited pool of child and adolescent mental health providers, is an urgent public health priority. A meta-analysis of 12 randomized controlled trials (RCTs) of yoga for depressive symptoms in adults reported yoga was significantly better than usual care, relaxation, or aerobic exercise in decreasing depressive symptoms. We recently conducted a 10-week RCT of adjunctive hatha yoga (vs. a health education control) for adults with current or recent major depression, on antidepressant treatment, yet continued to have depressive symptoms (n=122). Between-group differences in depression symptom severity, while not statistically significant at 10 weeks, were significantly different at the 6-month follow-up period, favoring yoga. Thus, even in this difficult-to-treat group of adults, hatha yoga had an enduring effect on depressive symptoms. There are various plausible mechanisms by which yoga may have an impact on depression, including self- regulatory mechanisms. Yoga may increase self-compassion and one?s ability to observe one?s thoughts and feelings as subjective and transient internal experiences rather than objective and permanent reality (i.e., meta-cognitive awareness). It may also lead to increased heart rate variability, reflecting an improved ability to regulate one?s biological and other responses to stress. To our knowledge, there have not been any studies that rigorously examined yoga in adolescents with clinically significant depression symptoms. Given yoga?s promising results in adults, we believe that hatha yoga may be a useful and safe intervention for depression in adolescents. Using the Participatory Action Research framework, we propose to adapt yoga for adolescents using step-wise guidelines for adapting manualized interventions which include conducting separate focus groups with adolescents (n=24) and parents; soliciting feedback from experts; making iterative revisions of an instructor manual, and conducting pilot open (n=12) and randomized controlled trials (n=40). We will compare yoga to group CBT, to assess feasibility, acceptability, safety, and within-group changes on depression symptom severity (primary outcome) and functional impairment and anxiety (secondary outcomes), as well as changes in potential mechanisms of action, including self-compassion, meta-cognitive awareness, and heart rate variability. This pilot project will provide us with procedures, manuals, and supportive data on feasibility and acceptability that will prepare us to conduct a fully-powered noninferiority design trial of hatha yoga vs. group CBT for depression in adolescents.